Sanding and polishing machine



A. .1. DREMEL 2,721,427

SANDING AND POLISHING MACHINE Oct. 25, 1955 Filed April 24, 1953 2 Sheets-Sheet l INVENTOR ALBERT J. DREMEL.

ATTORNEYS Oct. 25, 1955 A DREMEL SANDING AND POLISHING MACHINE 2 Shoeta$heot 2 Filed April 24, 1953 INVENTOR ALBERT J. DR EMEL ATTORNEYS United States Patent SANDING A'ND POLISHING MACHINE Albert J. Dremel, Racine, Wis., assignor to Dremel Manufacturing Company, Racine, Wis., a corporation of Wisconsin Application April 24, 1953, Serial No. 350,828

6 Claims. (Cl. 51-170) This invention appertains to portable sanding, polishing and like machines of the type embodying a motor and a reciprocating work plate driven from the motor.

One of the primary objects of my invention, is to provide a sanding and polishing machine having a compact and durable arrangement of parts, whereby to bring about a light weight machine of a small size which will be rugged and powerful in use in comparison to its size.

Another salient object of my invention is to provide a novel and simple frame for the electric motor, whereby the motor can be conveniently and easily mounted within and connected to the casing or housing of the machine and whereby the resilient supports for the work plate can be effectively carried by the motor frame.

A further object of my invention is to'provide a pair of flat parallel springs secured to the motor frame and to the work plate for effectively supporting and guiding the work plate in a substantially straight path during the driving of the plate from the rotary armature shaft of the motor, so as to eliminate guide tracks and the like, and the friction set up thereby.

A further object of my invention is to provide novel means for cooling the motor, the housing and the manipulating hand grip carried by the housing to effectively prevent over-heating of the motor and to insure ease in the handling of the sander.

Another further object of my invention is to provide a sanding and polishing machine embodying a novel work plate including a detachable pad and sand paper holding plate for connection quickly with a permanent work plate, whereby different characters of work can be done, such as wet sanding and the like, without affecting the permanent work plate carried by the machine.

A further important object of my invention, is to provide a simple and convenient means for connecting the detachable plate for the pad and sand paper with the permanent work plate.

A still further object of my invention is the provision of spring clips for holding the sand paper on the removable plate and over the pad with the clips so arranged that when the removable plate is associated with the permanent work plate, the permanent work plate will aid in holding the clips in desired griping contact with the sand paper.

With these and other objects in view, the invention consists in the novel construction, arrangement and formation of parts, as will be hereinafter more specifically described and claimed, and illustrated in the accompanying drawings, in which drawings,

Figure 1 is a longitudinal sectional View through my improved sanding and polishing machine.

Figure 2 is a transverse sectional view through the machine, taken on line 22 of Figure 1, looking in the direction of the arrows and illustrating more particularly the novel spring connection between the frame of the motor and the reciprocating work plate.

Figure 3 is a horizontal sectional view taken on the line 33 of Figure 3, looking in the direction of'the arrows'and illustrating the top frame of the motor and the connection of the springs therewith for supporting the work plate and guiding it.

Figure 4 is a horizontal sectional view taken onthe line 44 of Figure 1, looking in the direction of the arrows, and showing the work plate in top plan with the releasable latches carried by the permanent part of the work plate and detachably holding the removable plate in position.

Figure 5 is a horizontal sectional view, taken on the line 55 of Figure 1, looking in the direction of the arrows and showing the removable part of the work plate in top plan.

Figure 6 is a fragmentary detail transverse sectional view taken on the line 6-6 of Figure 1, illustrating a part of the drive for the work plate.

Figure 7 is a fragmentary detail longitudinal sectional view taken on the line 7-7 of Figure 4, looking in the direction of the arrows, and illustrating the engagement of the permanent part of the work plate with the sand paper holding clips carried by the removable plate.

Referring to the drawings in detail, wherein similar reference characters designate corresponding parts throughout the several views, the letter M generally indicates the novel polishing and sanding machine, and the same includes a rotary electric motor 10 of an approved type, and this motor embodies field laminations 11 and coils 12. Mounted within the field laminations 11 and coils 12 is a rotary armature 13. The armature 13 includes and armature shaft 14 and the opposite ends of the shaft are rotatably mounted in suitable bearings 15 carried by upper and lower bearing caps 16 and 17 which form a part of the motor frame 18. The motor frame 18 is especially designed in accordance with my invention to facilitate the mounting of the motor within the housing 19 and for supporting certain of the parts of the machine as will later appear.

The frame 18 includes an upper substantially rectangular section 20 and a similar lower substantially rectangular section 21, and the laminations 11 are clamped between the sections 20 and 21 of the frame. The opposite ends of the sections 20 and 21 adjacent to the corners thereof, are provided with vertically aligned bosses 22 and machine screws 23 are received within the bosses for firmly holding the sections together. By referring to Figures 2 and 3, it will be noted that the sections 20 and 21 carry webs 24 for supporting the bearing caps 15. Formed on the upper frame section 20, at the opposite ends thereof, are arms 25 and 26 and the opposite outer faces of these arms are recessed, as at 27, to snugly receive the upper ends of spaced parallel fiat leaf springs 28 and 29. These leaf springs extend beyond one end of the motor, for a purpose, which will also be hereinafter more fully described. The upper ends of the springs 28 and 29 are firmly secured within the recesses 27 and to the motor frame by the use of machine screws 30. Formed on the arm 25 is a lug 31. The lower frame section 21 has formed on its opposite sides laterally extending lugs 32. The lugs 31 and 32 constitute means whereby the motor can be firmly secured within the housing 19, and this will be more fully described.

The armature shaft 14 extends below the frame and between the outer ends of the springs 28 and 29 and the extreme outer end of the armature shaft is provided with an eccentric crank arm 33 and the shaft is also provided with counterbalancing weight 34. Cooling fans 35 are also preferably secured to the armature shaft for rotation therewith.

The eccentric crank arm 33 forms a part of the mechanism for reciprocating a work plate 36 which forms an important part of my invention.

As illustrated, the housing or casing 19, includes an upper section 37 preferably shaped to correspond to the configuration of the motor and the lugs 31 and 32 receive the holding screws 38 which extend through the housing section 37. The housing 19 also includes a lower section 39, which is preferably shaped to conform somewhat to the shape of the work plate 36. This lower section 39 includes spaced parallel longitudinally extending side walls 40, end walls 41 and a top wall 42. A part of the top wall is open so that the sections 37 and 39 have interior communication. The inner end of the housing section 37 at spaced points has formed thereon attaching lugs 43 so that the sections 37 and 39 can be secured together by the use of screws 44 or the like. The upper section 37 can have formed thereon or secured thereto, an elongated operating handle 45 through which the cord 46 carrying the electric wires for the motor can extend. Opposite to the handle 45, the housing carries a handle knob 47. The arrangement of the handle as and the knob -37 provides a convenient means for manipulating the sander by a workman.

Now referring more particularly to the work plate 36, the same includes a permanent plate section 43 formed of sheet metal of the desired gauge, and this plate section 48 is secured to and is carried by the outer ends of the springs 28 and 29. The outer ends of the springs have formed thereon feet 49 which are riveted or otherwise secured to the plate section. The outer end of the spring 29 is also bifurcated, as at 50, for a purpose which will later appear. The longitudinal sides of the permanent plate section 4% are upturned to provide flanges 51, and these flanges ride between side walls 40 of the lower section 39 of the housing 19 and these flanges function to keep dust and dirt out of the housing.

Arranged in facial relation to the plate section 48 is a removable plate section 52 which can be wider than the permanent plate section 48. The outer face of the removable plate section 52 has secured thereto a pad 53 and the plate section over the pad 53 carries a strip of sand paper 54 or other abrasive material. To removably hold the strip 54 in place, the inner surface of the removable plate section 52, at its opposite ends carries spaced spring clips 55 and the inner ends of the clips are riveted, as at 56, or otherwise secured to the removable plate section 52. The ends of the strip 54 are slipped between the free ends of the springs and the adjacent surface of the plate section 52. Struck up from the plate 52, adjacent to its opposite ends and between the spring clips 55 are apertured ears 57. These ears are received in transverse slots 58 formed in the permanent plate section 48 when the plate sections 48 and 52 are in their assembled position.

To effectively and detachably secure the plate sections together, the permanent plate section 48 has pivoted thereto adjacent to its opposite ends, latch arms 59. Each latch arm is provided with a resilient arcuately curved latch finger 6%, and by swinging the latches 59 to move the resilient fingers 60 in the apertures of the ears 57, the removable plate 52 can be detachably latched to the permanent plate section 48. The resilient fingers bear down on the exposed surface of the Plate section 48 and against the upper walls of the apertures of the ears 57. Each latch is also provided with a manipulating fingerpiece 61, and these fingerpieces normally lie adjacent to the extreme outer edges of the plate section 48 so that the latches can be easily grasped and swung on their pivots into and out of latching engagement with the cars 57. To slightly space the plate section 52 from the permanent plate section 48, the plate section 52 can have struck up therefrom rounded knobs 62, but it is to be understood that when the plates are in their assembled position, the plate section 48 will bear down on the outer ends of the clips 55 so as to hold the clips in firm gripping contact with the terminals of the sand paper strip 54.

Now referring to the drive for the work plate 36 and moreparticularly to Figures 1 and 4, it can be seen that the eccentric crank 33 carries, by means of bearings 63, a crank arm 64 and that the outer end of the crank arm receives in a resilient sleeve 65, a drive pin 66 rigidly carried by the permanent plate section 48 of the work plate 36. The crank arm extends through the bifurcated portion 59 of the spring 29 and hence the spring 29 will not interfere with the driving of the work plate.

Great stress is laid on the arrangement of the springs 28 and 29 relative to the drive, and these springs support and guide the work plate during the reciprocation thereof by the drive mechanism, and effectively prevent lateral movement of the work plate. As the upper ends of the springs are firmly anchored within the arms 25 and 26 on the motor frame, swinging of these arms laterally is prevented.

In use of my improved machine, and considering that the latches 59 are swung outwardly to their dotted line position, illustrated in Figure 5, then the desired grade and character of a sand paper or like strip 52 is secured to the removable plate section 52 by the clips 55, as heretofore described, and the plate section 52 is then mounted on the plate section 48, by passing the ears 57 through the slots 58 of the plate section 48. The latches are now pressed inwardly and the removable plate section is now mounted for movement with the permanent plate section 48. Upon closing the circuit through the motor, the entire work plate 36 will be reciprocated and aided in its movement by the springs 28 and 29 in the desired straight path. A switch 67 can be carried by the handle 45 for controlling the circuit to the motor.

By having the removable plate section 52, various types of sanding can be accomplished without injury to the permanent work plate 43, and the removable plate section 52 is particularly useful in wet sanding and the like.

By referring to Figures 1 and 3, it can be seen that the operating handle 45 is of a hollow construction and that the inner end thereof opens into the interior of the housing 19 adjacent to the upper end thereof. The outer end of the handle 45 is provided with an air escape opening 68 below the cord 46. The fans 35 create a flow of air in the housing past the motor and through the housing and, thence, through the handle 45 and out of the opening 68. This effectively cools the motor, the housing and the manipulating handle. Great stress is laid on the passage of air through the housing and the handle, and obviously the handle is maintained in a cooled condition and facilitates the handling of the machine by a workman, even though the sander is operated continuously for a considerable length of time.

Various changes in details may be made without departing from the spirit or the scope of my invention, but what I claim as new is:

1. In a sanding and polishing machine, a motor including a frame and a rotary armature shaft extending beyond the frame, said frame having attaching lugs, a housing receiving the motor and secured to the motor by the lugs on said frame, said frame also having arms at its opposite ends provided with recesses, a reciprocating Work plate, means operatively connecting the armature shaft to the work plate and supporting and guiding springs for the work plate secured to the plate on opposite sides of the armature shaft, the inner ends of said springs being received in the recesses in the arms and confined against lateral shifting, and means securing the inner ends of the springs to the arms.

2. In a sanding and polishing machine a rotary electric motor including laminated field plates and windings,

a rotary armature shaft and a frame including upper and lower sections receiving the laminations, means securing the frame sections together for holding the laminations, arms on the upper frame section at the opposite ends thereof having their outer faces recessed, an attaching lug on one of said arms, and laterally extending attaching lugs on the lower frame section, a housing receiving the motor, means detachably securing the housing to said lugs, a reciprocating work plate arranged beyond one end of the housing, means operatively connecting the armature shaft to the work plate, and supporting and guiding springs for the work plate secured to the plate on opposite sides of the armature shaft with the inner ends of said arms received in said recesses and held against lateral shifting movement by the walls thereof, and means securing the inner ends of said springs to the arms.

3. In a sanding and polishing machine, a housing, a work plate arranged beyond one side of the housing for reciprocating movement including an inner permanent plate section and a removable outer plate section, means in said housing for reciprocating the work plate and operatively connected to the permanent inner plate section, means for detachably securing an abrasive strip to the outer plate section and said outer plate section having a pair of spaced apertured ears, said permanent inner plate section having slots receiving said ears, and pivoted latches mounted upon the permanent inner plate section movable into and out of apertures of said ears when said ears are extended through the slots.

4. In a sanding and polishing machine as defined in claim 3 and said pivoted latches each including arcuately curved resilient latch fingers adapted to bear against the exposed face of the permanent plate section and the walls of the apertures of the ears when said fingers are moved in said apertures.

5. In a sanding and polishing machine as defined in claim 4, and manipulating fingerpieces on said latches disposed adjacent to the opposite ends of said permanent inner plate section.

6. In a sanding and polishing machine as defined in claim 4 and said latches being pivoted on the opposite sides of the longitudinal axis of the inner plate section.

References Cited in the file of this patent UNITED STATES PATENTS 1,294,398 Cavicchi Feb. 18, 1919 2,079,143 Albertson May 4, 1937 2,193,413 George Mar. 12, 1940 2,395,537 Crosby Feb. 26, 1946 2,441,506 Osman May 11, 1948 2,492,231 Mandl Dec. 27, 1949 2,517,548 Dobson Aug. 8, 1950 2,565,658 Hilger Aug. 28, 1951 2,585,637 Dremel Feb. 12, 1952 2,614,369 Robins Oct. 21, 1952 2,697,898 Osman Dec. 28, 1954 

